Die Carbonylchrom-, Carbonylmolybdaen- und Carbonylwolfram-Komplexe der Unsymmetrisch Substituierten Phosphinoschwefeldiimide tBu2P(NSN)PPh2 und tBu2P(NSN)P(tBu)Ph. 1H, 13C und 31P NMR-Spektroskopische Charakterisierung

Article abstract of DOI:10.1016/0022-328X(91)80005-5

In addition to the carbonylmetal complexes of bis(di-tert-butylphosphino) sulfur diimide, ^tBu2P(NSN)P^tBu2 (1), carbonylmetal derivatives of the unsymmetrically substituted phosphino sulfur diimides ^tBu2P(NSN)PPh2 (2) and ^tBu2P(NSN)P(^tBu)Ph (3) have been prepared and characterized by NMR, IR and mass spectroscopy.In the presence of THF-stabilized pentacarbonylmetal 16-electron complex fragments, (M = Cr (a), Mo (b), W (c)), 2 and 3 react to give binuclear complexes <(CO)5M>^tBu2P(NSN)P(R)Ph (R = Ph (4a-c), ^tBu (5a-c).The norbornadiene compounds M(CO)4(nor-C7H8) can be used to prepare chelate complexes of 2 and 3 with 14-electron complex fragments, , i.e. ^tBu2P(NSN)P(R)Ph (R = Ph (6a-c), ^tBu (7a-c).The structures of the new complexes were established on the basis of their 1H, 13C and 31P NMR spectra.As a result of the different substitution at the two phosphorus centers in 2 and 3, a variety of NMR parameters can be obtained which are not easily accessible for symmetrically substituted phosphino sulfur diimides such as 1 and their metal complexes.On the basis of the 31P NMR spectra it is assumed that the binuclear complexes 4a-c and 5a-c are fluxional molecules in solution and undergo configurational Z/E<*>E/Z interconversion; no significant signal broadening or splitting could be observed down to -90 deg C in the cases of S(N-P^tBu2)2 and <(CO)5Mo>^tBu2P(NSN)PPh2 (4b).Hahn-spin-echo experiments were used to determine coupling constants ¹J(31P,15N).The 13C-NMR spectra of the chiral chelate complexes ^tBu2P(NSN)P(^tBu)Ph (7a-c) are temperature-dependent, indicating restricted rotation of the phenyl substituent around the P-C bond (ΔG^<*> = 57.1 +/- 1 kJ/mol in 7c).